Fix comparing key and mark prefix/suffix as optional.

src/compare/compare_field.rs

@@ -14,7 +14,6 @@ use crate::types::AstNode;
 #[derive(Debug)]
 pub(crate) enum EmacsField<'s> {
     Required(&'s str),
-    #[allow(dead_code)]
     Optional(&'s str),
 }
 

src/compare/diff.rs

@@ -3492,13 +3492,21 @@ fn compare_citation<'b, 's>(
             compare_property_quoted_string
         ),
         (
-            EmacsField::Required(":prefix"),
-            |r| Some(r.prefix.iter()),
+            EmacsField::Optional(":prefix"),
+            |r| if r.prefix.is_empty() {
+                None
+            } else {
+                Some(r.prefix.iter())
+            },
             compare_property_list_of_ast_nodes
         ),
         (
-            EmacsField::Required(":suffix"),
-            |r| Some(r.suffix.iter()),
+            EmacsField::Optional(":suffix"),
+            |r| if r.suffix.is_empty() {
+                None
+            } else {
+                Some(r.suffix.iter())
+            },
             compare_property_list_of_ast_nodes
         )
     ) {
@@ -3544,13 +3552,21 @@ fn compare_citation_reference<'b, 's>(
             compare_property_quoted_string
         ),
         (
-            EmacsField::Required(":prefix"),
-            |r| Some(r.prefix.iter()),
+            EmacsField::Optional(":prefix"),
+            |r| if r.prefix.is_empty() {
+                None
+            } else {
+                Some(r.prefix.iter())
+            },
             compare_property_list_of_ast_nodes
         ),
         (
-            EmacsField::Required(":suffix"),
-            |r| Some(r.suffix.iter()),
+            EmacsField::Optional(":suffix"),
+            |r| if r.suffix.is_empty() {
+                None
+            } else {
+                Some(r.suffix.iter())
+            },
             compare_property_list_of_ast_nodes
         )
     ) {

src/parser/citation_reference.rs

@@ -1,6 +1,7 @@
 use nom::branch::alt;
 use nom::bytes::complete::tag;
 use nom::character::complete::anychar;
+use nom::combinator::map;
 use nom::combinator::not;
 use nom::combinator::opt;
 use nom::combinator::recognize;
@@ -56,18 +57,22 @@ pub(crate) fn citation_reference_key<'b, 'g, 'r, 's>(
     context: RefContext<'b, 'g, 'r, 's>,
     input: OrgSource<'s>,
 ) -> Res<OrgSource<'s>, OrgSource<'s>> {
-    let (remaining, source) = recognize(tuple((
-        tag("@"),
-        many1(verify(
-            preceded(
-                not(parser_with_context!(exit_matcher_parser)(context)),
-                anychar,
-            ),
-            |c| {
-                WORD_CONSTITUENT_CHARACTERS.contains(*c) || "-.:?~`'/*@+|(){}<>&_^$#%~".contains(*c)
-            },
+    let (remaining, source) = map(
+        tuple((
+            tag("@"),
+            recognize(many1(verify(
+                preceded(
+                    not(parser_with_context!(exit_matcher_parser)(context)),
+                    anychar,
+                ),
+                |c| {
+                    WORD_CONSTITUENT_CHARACTERS.contains(*c)
+                        || "-.:?~`'/*@+|(){}<>&_^$#%~".contains(*c)
+                },
+            ))),
         )),
-    )))(input)?;
+        |(_, key)| key,
+    )(input)?;
     Ok((remaining, source))
 }